In both one-way paging and two-way messaging, duplicate messages may be sent to a selective call device such as a selective call receiver or transceiver for a variety of reasons. A one-way paging system may intentionally be designed to send duplicate messages to create (at the expense of system latency and capacity) greater reliability through time diversity, such as in Motorola's FLEX-TD paging system used in Japan. In each instance, there are several factors that creates complications in the processing of such duplicate messages. For instance, when messages are sent multiple times in an unreliable radio frequency environment, errored characters are received. Most errors are corrected using forward error correction, but some errors are only detected. Other codewords in the message may be so badly corrupted that they correct to the wrong codeword. When a badly corrupted portion of a message corrects to a wrong codeword or character, falsing occurs and detection of duplicate messages becomes a significant problem. In current alphanumeric two-way paging, for example, detected errors are handled in duplicate message processing by treating them as wildcards that match any character in future versions of that repeated message. This causes the user to only see one version of the message to be displayed. However, falsed characters are not treated as wildcards, and therefore the entire message shows up as a new message which the user sees as an undesirable duplicate message on their display. Thus, a need exists for a duplicate message processing method and apparatus that recognizes the problem encountered with falsing of error corrected messages and that appropriately handles such duplicate messages by avoiding the repeat display or alerting of such duplicate messages.
In a two-way messaging environment, a message may be resent to a selective call transceiver (pager) because the message was not delivered well (possibly had too many errors), or an acknowledgment was not received by the two-way messaging system. In any instance, the same message will be received by the pager, wherein the pager has the option to retain errored messages. Most two-way pagers enable this option because the first message received may be the only message it receives and the user may want an opportunity to view such messages despite the error level the message contains. Additionally, for both one-way and two-way device, the ability to recognize a duplicate message is further complicated by the fact that the user or the pager itself could delete a previously received message. Thus, a pager user that deletes a message because of convenience (i.e., message was read and occupied unnecessary space in memory) may receive a duplicate message without an adequate means of detecting such duplicate as a result of the previous deletion. Of course, a pager user or a pager itself that deleted a message failing to meet a certain threshold of quality would want to receive a subsequent duplicate message. Therefore, a need also exists for a selective call device and method of operation of such device that would logically detect whether a page was deleted for convenience or for quality reasons and appropriately handle subsequent duplicate messages with minimal burden on the user.